Fresh frozen cadaveric osseous and osteoarticular allograft transplants have been used in the treatment of malignant and aggressive bone tumors in 115 patients with general success (75% good or excellent with longest folloup of 9.5 years). Numerous questions remain regarding optimal methods for cryopreservation, immunosuppression, revasularization and, in fact, the fate of the grafts and methods of avoiding the complications of fracture, infection and non union. The investigators plan to continue a series of studies to evaluate the biology of allograft transplants in man and animal models in order to make the technique more reliable and predictably successful. The studies include: (1) continued in-depth follow-up of the patient series in terms of the fate of the graft and the effect on the host immune system. Special techniques for study of the graft include CT and radionuclie scanning; (2) continued study of banking practices with special emphasis on computer graphic modeling of segments for optimal sizing; (3) further development of the cat model to allow additional experiments to assess the mechanical strength of the graft at various periods after implant, the mcrovasulture, the effect on the immune system of the host, the biology of alteration of the articular cartilage and the effect of short-term immunosuppression with such agents as cyclosporin A, small transfusions, ALG and ATG; and (4) continued attempts at improvement of retention of viability of cartilage by introduction of cryoprotective agents prior to freezing.